Biblio

A wireless communication system with rotating linearly polarized antennas is built and tested as a method for increasing physical layer security. Controlling the linear polarization angle from 0° to 180° yields bit error rates greater than 20% for 40° of rotation.

Over time, the use of wireless technologies has significantly increased due to bandwidth improvements, cost-effectiveness, and ease of deployment. Owing to the ease of access to the communication medium, wireless communications and technologies are inherently vulnerable to attacks. These attacks include brute force attacks such as jamming attacks and those that target the communication protocol (Wi-Fi and Bluetooth protocols). Thus, there is a need to make wireless communication resilient and secure against attacks. Existing wireless protocols and applications have attempted to address the need to improve systems security as well as privacy. They have been highly effective in addressing privacy issues, but ineffective in addressing security threats like jamming and session hijacking attacks and other types of Denial of Service Attacks. In this article, we present an ``architecture for resilient wireless communications'' based on the concept of Moving Target Defense. To increase the difficulty of launching successful attacks and achieve resilient operation, we changed the runtime characteristics of wireless links, such as the modulation type, network address, packet size, and channel operating frequency. The architecture reduces the overhead resulting from changing channel configurations using two communication channels, in which one is used for communication, while the other acts as a standby channel. A prototype was built using Software Defined Radio to test the performance of the architecture. Experimental evaluations showed that the approach was resilient against jamming attacks. We also present a mathematical analysis to demonstrate the difficulty of performing a successful attack against our proposed architecture.

The wireless communication is a backbone for a development of a nation. But spectrum is finite resource and issues like spectrum scarcity, loss of signal quality, transmission delay, raised in wireless communication system due to growth of wireless applications and exponentially increased number of users. Secondary use of a spectrum using Software Defined Radio (SDR) is one of the solutions which is also supported by TRAI. The spectrum sensing is key process in communication based on secondary use of spectrum. But energy consumption, added delay, primary users security are some threats in this system. Here in this paper we mainly focused on throughput optimization in secondary use of spectrum based on optimal sensing time and number of Secondary users during cooperative spectrum sensing in Cognitive radio networks.

Internet of Things (IoT) devices industry is rapidly growing, with an accelerated increase in the list of manufacturers offering a wide range of smart devices selected to enhance end-users' standard of living. Security remains an after-thought in these devices resulting in vulnerabilities. While there exists a cryptographic protocol designed to solve such authentication problem, the computational complexity of cryptographic protocols and scalability problems make almost all cryptography-based authentication protocols impractical for IoT. Wireless RFF (Radio Frequency Fingerprinting) comes as a physical layer-based security authentication method that improves wireless security authentication, which is especially useful for the power and computing limited devices. As a proof-of-concept, this paper proposes a universal SDR (software defined Radio)-based inexpensive implementation intended to sense emitted wireless signals from IoT devices. Our approach is validated by extracting mobile phone signal bursts under different user-dedicated modes. The proposed setup is well adapted to accurately capture signals from different telecommunication standards. To ensure a unique identification of IoT devices, this paper also provides an optimum set of features useful to generate the device identity fingerprint.

Electromagnetic noise emitted from running computer displays modulates information about the picture frames being displayed on screen. Attacks have been demonstrated on eavesdropping computer displays by utilising these emissions as a side-channel vector. The accuracy of reconstructing a screen image depends on the emission sampling rate and bandwidth of the attackers signal acquisition hardware. The cost of radio frequency acquisition hardware increases with increased supported frequency range and bandwidth. A number of enthusiast-level, affordable software defined radio equipment solutions are currently available facilitating a number of radio-focused attacks at a more reasonable price point. This work investigates three accuracy influencing factors, other than the sample rate and bandwidth, namely noise removal, image blending, and image quality adjustments, that affect the accuracy of monitor image reconstruction through electromagnetic side-channel attacks.

This paper describes and verifies a method of implementing bit error rate (BER) calculation for FPGA-based physical layer security techniques for Software Defined Radio (SDR). Specifically, we describe an independent source signal processing architecture for an efficient calculation of BER for wireless communication modules across the transmitter and receiver nodes. The source components at the transmitter and the receiver both generate identical random bits independently from each other, allowing for the received data to be compared to the original bit stream to calculate BER completely on hardware. The described method is implemented on a Xilinx Virtex-6 ML605 FPGA and reduces processing time by more than four orders of magnitude less than hardware simulation techniques in regression testing and validation over billions of bits, shortening design turn around times and accelerating Physical layer based security development for wireless communication research. The described independent source approach utilizes a minimal amount of board resources, allowing it to be integrated seamlessly into SDR hardware designs. Experimental validation of the independent source based BER calculation is performed for an Orthogonal Frequency Division Multiplexing signal, and a comparison between different stages of hardware design for the execution time required for BER testing of a large number of bits is provided.

As the use of wireless technologies increases significantly due to ease of deployment, cost-effectiveness and the increase in bandwidth, there is a critical need to make the wireless communications secure, and resilient to attacks or faults (malicious or natural). Wireless communications are inherently prone to cyberattacks due to the open access to the medium. While current wireless protocols have addressed the privacy issues, they have failed to provide effective solutions against denial of service attacks, session hijacking and jamming attacks. In this paper, we present a resilient wireless communication architecture based on Moving Target Defense, and Software Defined Radios (SDRs). The approach achieves its resilient operations by randomly changing the runtime characteristics of the wireless communications channels between different wireless nodes to make it extremely difficult to succeed in launching attacks. The runtime characteristics that can be changed include packet size, network address, modulation type, and the operating frequency of the channel. In addition, the lifespan for each configuration will be random. To reduce the overhead in switching between two consecutive configurations, we use two radio channels that are selected at random from a finite set of potential channels, one will be designated as an active channel while the second acts as a standby channel. This will harden the wireless communications attacks because the attackers have no clue on what channels are currently being used to exploit existing vulnerability and launch an attack. The experimental results and evaluation show that our approach can tolerate a wide range of attacks (Jamming, DOS and session attacks) against wireless networks.

A novel physical layer authentication scheme is proposed in this paper by exploiting the time-varying carrier frequency offset (CFO) associated with each pair of wireless communications devices. In realistic scenarios, radio frequency oscillators in each transmitter-and-receiver pair always present device-dependent biases to the nominal oscillating frequency. The combination of these biases and mobility-induced Doppler shift, characterized as a time-varying CFO, can be used as a radiometric signature for wireless device authentication. In the proposed authentication scheme, the variable CFO values at different communication times are first estimated. Kalman filtering is then employed to predict the current value by tracking the past CFO variation, which is modeled as an autoregressive random process. To achieve the proposed authentication, the current CFO estimate is compared with the Kalman predicted CFO using hypothesis testing to determine whether the signal has followed a consistent CFO pattern. An adaptive CFO variation threshold is derived for device discrimination according to the signal-to-noise ratio and the Kalman prediction error. In addition, a software-defined radio (SDR) based prototype platform has been developed to validate the feasibility of using CFO for authentication. Simulation results further confirm the effectiveness of the proposed scheme in multipath fading channels.
 

Sampling and reconstruction (S&R) are used in virtually all areas of science and technology. The classical sampling theorem is a theoretical foundation of S&R. However, for a long time, only sampling rates and ways of the sampled signals representation were derived from it. The fact that the design of S&R circuits (SCs and RCs) is based on a certain interpretation of the sampling theorem was mostly forgotten. The traditional interpretation of this theorem was selected at the time of the theorem introduction because it offered the only feasible way of S&R realization then. At that time, its drawbacks did not manifest themselves. By now, this interpretation has largely exhausted its potential and inhibits future progress in the field. This tutorial expands the theoretical foundation of S&R. It shows that the traditional interpretation, which is indirect, can be replaced by the direct one or by various combinations of the direct and indirect interpretations that enable development of novel SCs and RCs (NSCs and NRCs) with advanced properties. The tutorial explains the basic principles of the NSCs and NRCs design, their advantages, as well as theoretical problems and practical challenges of their realization. The influence of the NSCs and NRCs on the architectures of SDRs and CRs is also discussed.

While many theoretical and simulation works have highlighted the potential gains of cognitive radio, several technical issues still need to be evaluated from an experimental point of view. Deploying complex heterogeneous system scenarios is tedious, time consuming and hardly reproducible. To address this problem, we have developed a new experimental facility, called CorteXlab, that allows complex multi-node cognitive radio scenarios to be easily deployed and tested by anyone in the world. Our objective is not to design new software defined radio (SDR) nodes, but rather to provide a comprehensive access to a large set of high performance SDR nodes. The CorteXlab facility offers a 167 m2 electromagnetically (EM) shielded room and integrates a set of 24 universal software radio peripherals (USRPs) from National Instruments, 18 PicoSDR nodes from Nutaq and 42 IoT-Lab wireless sensor nodes from Hikob. CorteXlab is built upon the foundations of the SensLAB testbed and is based the free and open-source toolkit GNU Radio. Automation in scenario deployment, experiment start, stop and results collection is performed by an experiment controller, called Minus. CorteXlab is in its final stages of development and is already capable of running test scenarios. In this contribution, we show that CorteXlab is able to easily cope with the usual issues faced by other testbeds providing a reproducible experiment environment for CR experimentation.